A number of ultrasonic devices have heretofore been proposed for use in ablating or removing obstructive material from anatomical structures, such as blood vessels. Examples of devices which purportedly utilize ultrasonic energy, alone or in conjunction with other treatment modalities, to remove obstructions from anatomical structures include those described in U.S. Pat. Nos. 3,433,226 (Boyd), 3,823,717 (Pohlman, et al.), 4,808,153 (Parisi), 4,936,281 (Stasz), 3,565,062 (Kuris), 4,924,863 (Sterzer), 4,870,953 (Don Michael, et al.), 4,920,954 (Alliger, et al.), and 5,100,423 (Fearnot) as well as other patent publications W087-05739 (Cooper), W089-06515 (Bernstein, et al.), W090-0130 (Sonic Needle Corp.), EP316789 (Don Michael, et al.), DE3,821,836 (Schubert) and DE2,438,648 (Pohlman).
Ultrasound transmitting catheters have been utilized to successfully ablate various types of obstructions from blood vessels of humans and animals. Patients who are candidates for ultrasound ablation of vascular obstructions may also be candidates for treatment by various thrombolytic agents (i.e., blood clot dissolving agents) or other therapeutic agents or drugs.
Many types of therapeutic agents or drugs may be delivered by the ultrasonic catheter of the present invention. The types of agents or drugs which may be utilized in cardiovascular applications of the catheter include, but are not necessarily limited to, the following:
i. Thrombolytic Agents
Examples of thrombolytic agents utilized to dissolve thrombotic material include: streptokinase (Streptokinase for Infusion, Astra Pharmaceutical Products, Inc., Westboro, Mass., and Kabikinase.RTM., Kabi Pharmacia, Piscataway, N.J.); urokinase (Abbokinase.RTM., Abbott Laboratories, North Chicago, Ill..); and tissue plasminogen activator (TPA). Such agents are administered intravascularly following myocardial infarction or other cardio vascular events wherein a thrombus is suspected to be in formation or in existence.
ii. Anticoagulant Agents
Examples of anticoagulant agents utilized to prevent the subsequent formation of thrombus or blood clots include heparin (Heparin Sodium Injection, Wyeth-Ayerst Laboratories Philadelphia, Pa.).
In patients who are undergoing ultrasonic angioplasty procedures wherein a vascular obstruction is ablated by way of ultrasonic vibration, the administration of one or more therapeutic agents or drugs may be indicated before, during or after ultrasonic ablative procedure. Thus, it is desirable to design an ultrasonic ablation catheter through which various therapeutic agents or drugs may be delivered.
Additionally, it is desirable to design and devise new catheter devices for concurrently delivering a flow of liquid medicament along with ultrasonic vibration such that the distribution, delivery, absorption and/or efficacy of the medicament may be improved or enhanced by the ultrasonic vibration.